Example 2
A hemolysis assay was performed with C5-depleted sera and biotinylated C5 and non-biotinylated C5 to compare the lysis activities of C5 before and after biotinylation. Antibody-sensitized sheep erythrocytes (Complement Technology, Tyler Tex.) in solution at 5×108 cell/ml were centrifuged at 2,090×gravity for 3 minutes and resuspended in GVB++ buffer (Complement Technology, Tyler Tex.). C5-depleted human sera (Complement Technology, Tyler Tex.) was rapidly thawed at 37° C. and placed on ice until diluted in GVB−+. Non-biotinylated C5 protein (Complement Technology, Tyler Tex.) and biotinylated C5 protein (in-house biotinylation) was rapidly thawed at 37° C. and placed on a wet ice slurry until diluted in GVB++. 100 μl of cells (at a final concentration of 2.5×107 cells/ml) was combined with C5-depleted human sera and 50 μl biotinylated C5 or non-biotinylated C5 (with final concentrations of either 10 μg/ml, 3 μg/ml or 1 μg/ml) in a tissue culture-treated clear 96-well microtitre plate (USA Scientific, Ocala, Fla.). The plate was incubated for 1 hour at 37° C. After incubation, plates were then centrifuged at 2,090×gravity for 2 minutes before transferring 100 μl of supernatant to a new microtitre plate. Absorbance was read at 412 nm and percent lysis activity of non-biotinylated C5 and biotinylated C5 was compared.